Question

1- How much heat energy would be needed to convert 400g of gold at room temperature (25 ° C) to gold vapor at 3000 ° C?
2- How much heat energy would need to be removed from 800g of ethyl alcohol (ethanol) at 160 ° C and convert it into a solid at - 300 "c?
3- If 1200 calories of heat energy is added to 1.7 g diamond cutting tool that is at 25 ° C, what will be the final temperature of the diamond cutting tool?

- If 860 calories of heat energy is needed to raise the temperature of 14 g of a material from 47 ° C to 284 ° C, what is the specific heat of the material?

How much heat energy is needed to raise the temperature of 1500 g of water from - room temperature, 25 ° C, to the boiling point, 100 ° C?

Answer 1

#1.

q = m C ∆T

Where , q = heat absorbed or liberated (in joule)

m = mass of sample (grams) = 400 g

C = specific heat of substance = 0.126 J/g K

∆T = change in temperature in Kelvin , (3273k - 298k = 2975k )

As Kelvin = °C + 273 )

Putting values for (q) ;

q = 400g × 0.126 J/g k × 2975k = 149940 J = 149.94 kJ

Thus , 149.94 kJ heat is needed for this change in Temperature .